Gravitts are a species native to SR388 in Metroid II: Return of Samus. This creature hides in the floor, only coming out to attack when Samus comes close. When hidden, only the spike on top can be seen, which cannot be shot with a narrow-beamed weapon. Samus must jump over and shoot down at them while they are hidden. These creatures are notorious for hiding under destructible Sand blocks, so caution should be exercised when traveling on the bottom of a sandy area.
"It comes out of the ground and rushes at Samus, then darts back underground."